Nationwide Exposure of US Working Dogs to the Chagas Disease Parasite, Trypanosoma cruzi

Trypanosoma cruzi is a zoonotic protozoan parasite vectored by triatomine insects that are endemic to the Americas, including the southern United States. Surveillance of domestic dogs for T. cruzi exposure allows for the determination of geographic regions of transmission that are relevant for human and animal health. The U.S. Department of Homeland Security (DHS) working dogs provide critical security and detection services across the country, and many train or work in the southern United States, where they are at risk for T. cruzi exposure. We sampled blood from 1,610 working dogs (predominantly Belgian Malinois, German shepherds, and Labrador retrievers) from six task forces (including the Transportation Security Administration, Customs and Border Protection, Secret Service, and more) and two canine training centers across 41 states from 2015 to 2018. Canine sera that were reactive on at least two independent serological assays were considered positive for anti-T.-cruzi antibodies. In addition, up to three independent polymerase chain reaction (PCR) assays were used to detect and type T. cruzi DNA. Overall seroprevalence was 7.5%, and four dogs (0.25%, n = 1,610) had detectable parasite DNA in the blood, comprising parasite discrete taxonomic units (DTUs) TcIV and a coinfection of TcliTcIV. Dogs that worked within versus outside of the geographic range of established triatomines showed comparable seroprevalence (7.3% and 9.2%, respectively; P = 0.61). Determining the prevalence of T. cruzi in these working dogs and looking at spatially associated risk factors have practical implications for disease risk management and could assist with improved control measures to protect both animal and human health.